METHOD FOR PRODUCING PERFLUORINATED COPOLYMERS COMPRISING FUNCTIONAL SULFONYL FLUORIDE GROUPS

摘要

The invention relates to a method for producing perfluorinated copolymers comprising functional sulfonyl fluoride groups by copolymerisation of tetratorethylen with perfluorocarbonated vinyl ether of the structural formula CF2=CF-O-CF2-CF(CF3)-O-CF2-CF2-SO2F in a fluorine-containing organic solvent or in a mass under action of a radical-type initiator (perfluorinated peroxide) at an increase pressure associated with feeding a reaction medium with tetratorethylen during the copolymerisation process. Prior to the copolymerisation, a pre-prepared hydrolysed tetratorethylen copolymer containing 9.5-15.0 mol % of the perfluorocarbonated ether of said structural formula in a quantity of 0.3-0.66 % of the mass of the liquid reaction medium which is embodied in the form of a dispersion in the fluorine-containing organic solvent is introduced into the reaction medium. The perfluorinated peroxide is embodied in the form of peroxide selected from a group consisting of bis-perfluorine-(2-oxa-para-methyl-dioxane-propionyle)-peroxide, bis-perfluorine-(2,5,8-trimethyl-3,6,9-trioxa-dodecanoyle)-peroxide and bis-perfluorine-(cyclohexanoyl)-peroxide or the mixtures thereof. The process is carried out at a temperature of 20-35 DEG C and a pressure ranging from 0.25 to 0.6 MPa. The thus produced copolymer comprises 3.5-19 mol % of the perfluorocarbonated vinyl ether of the said structural formula. Said invention makes it possible to produce copolymers which can be transformed by extrusion into products whose thickness is less than 100 mkm and to form concentrated solutions used for producing thin cast films and fibres whose wall thickness ranges from 30 to 80 mkm.